Outdoor communication cabinet including fan tray and filter and method of detecting blockage of communication cabinet filter

ABSTRACT

An outdoor communication cabinet includes a housing having a interior, an opening into the interior and a door connected to the housing at the opening that includes a first aperture and a first fan tray with a plurality of fans, the fan tray being hingedly connected to the door for movement between first and second positions relative to the first aperture. Also a method of detecting blockage of filters in a communication cabinet.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional Patent Application No. 61/251,506 filed Oct. 14, 2009, the entire contents of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention is directed toward an improved outdoor communication cabinet for housing heat-producing electronic equipment that includes a fan tray and a filter and toward a method of detecting blockage of a communication cabinet filter, and, more specifically, toward an outdoor communication cabinet for electronic equipment that includes a door-mounted fan tray, a door-mounted filter for filtering air drawn into the cabinet by fans in the fan tray and a controller for controlling the fans and for detecting blockage of the filter.

BACKGROUND OF THE INVENTION

Outdoor cabinets for electronic and/or telecommunication equipment and connection panels are known in the art. The equipment in these cabinets generally must be maintained within a certain temperature range in order to function properly, and some of this equipment generates heat that must be dissipated. Direct air cooling is a common method for removing excess heat from such cabinets, especially when the equipment in the cabinet generates a relatively large amount of heat. In such systems, vents are also provided for allowing heat to escape from the cabinet interior and for allowing an air flow to pass through the cabinet over and around the equipment, which air flow may be produced or assisted by one or more fans. Screens or filters may also be provided to reduce the amount of particulate matter that finds its way into the cabinet interior, and any vent openings may be louvered to protect the cabinet interior from rain.

These outdoor cabinets may require periodic inspection to determine whether filters require replacement and whether the fan or fans in the cabinet are working properly. Filters that have become blocked may reduce air flow through the cabinet sufficiently that equipment in the cabinet overheats and malfunctions and may also lead to premature fan failure which further reduces the cooling capacity of the cabinet. It would therefore be desirable to determine automatically when a filter has become blocked and to mount one or more filters and the fan or fans in a manner that facilitates service and/or replacement when necessary and to permit scaling of the cooling system as need by the addition, deletion or changing of equipment in the cabinet.

SUMMARY OF THE INVENTION

These problems and others are addressed by embodiments of the present invention, a first aspect of which comprises an outdoor communication cabinet having a housing with a interior and an opening into the interior. A door is connected to the housing at the opening and includes a first aperture. A first fan tray, including a plurality of fans, is hingedly connected to the door for movement between first and second positions relative to the first aperture.

Another aspect of the invention comprises a method of detecting a degree of blockage of a filter in an outdoor communication which cabinet which includes a housing and at least one fan for driving air into the housing and a filter for filtering the air driven into the housing by the at least one fan. The method includes providing a sensor in the housing that provides an output based on a sensed pressure of the housing. The method also includes determining a first level of the output when the at least one fan is in a first state and determining a second level of the output when the at least one fan is in a second state. A relationship is determined between the first level and the second level and a signal is generated when the relationship satisfies a predetermined condition.

A further aspect of the invention comprises an outdoor communication cabinet that includes a housing with a interior and first and second openings into the interior. A door is connected to the housing at the first opening, and a fan tray, including a plurality of fans, is connected to the door. A damper is mounted at the second opening for regulating air flow through the second opening, and a controller is operatively connected to the plurality of fans and to the damper for controlling operation of the plurality of fans and a position of the damper.

Yet another aspect of the invention comprises a method of detecting a degree of blockage of a filter in an outdoor communication cabinet. The cabinet includes a housing having an interior with first and second openings into the interior, and a door is connected to the housing at the opening. The door includes an aperture, and a fan tray including a plurality of fans is hingedly connected to the door for movement between first and second positions relative to the first aperture. The filter is mounted to the door over the aperture on a side of the first fan tray opposite from the interior. A damper is mounted at the second opening for regulating air flow through the second opening, and a controller is operatively connected to the plurality of fans and to the damper for controlling operation of the plurality of fans and a position of the damper. The method includes providing a pressure sensor in the housing configured to provide an output based on a sensed pressure of the housing and connecting the pressure sensor to the controller. The method also includes determining a first level of the output when the at least one fan is in a first state, determining a second level of the output when the at least one fan is in a second state, determining a relationship between the first level and the second level, and generating a signal when the relationship satisfies a predetermined condition.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and features of the invention will be better understood after a reading of the following detailed description together with the attached drawings, wherein:

FIG. 1 is perspective view of an outdoor communication cabinet according to a first embodiment of the present invention, the door of the cabinet being shown in a partially open state.

FIG. 2 is a perspective view of the rear side of the door of FIG. 1 and a fan box mounted thereto.

FIG. 3 is a rear elevational view of the door of FIG. 2 with the fan box removed.

FIG. 4 is a rear elevational view of a modified version of the door of FIG. 2.

FIG. 5 is perspective view of the rear side of door of FIG. 2 showing an embodiment of the present invention that includes two fan boxes.

FIG. 6 is a perspective view of the door of FIG. 2 showing the fan box pivoted away from the door on a hinge.

FIG. 7 is a perspective view of the door of FIG. 2 showing the fan box pivoted away from the door and showing a first air filter partially removed from the fan box.

FIG. 8 is an exploded perspective view of the door of FIG. 2 showing a first air filter, a second air filter and a fan tray.

FIG. 9 is a sectional side elevational view taken along line IX-IX in FIG. 2.

FIG. 10 is a flow chart illustrating a method according to an embodiment of the invention.

DETAILED DESCRIPTION

The present invention now is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Like numbers refer to like elements throughout. In the figures, the thickness of certain lines, layers, components, elements or features may be exaggerated for clarity.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.

As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. As used herein, phrases such as “between X and Y” and “between about X and Y” should be interpreted to include X and Y. As used herein, phrases such as “between about X and Y” mean “between about X and about Y.” As used herein, phrases such as “from about X to Y” mean “from about X to about Y.”

It will be understood that when an element is referred to as being “on”, “attached” to, “connected” to, “coupled” with, “contacting”, etc., another element, it can be directly on, attached to, connected to, coupled with or contacting the other element or intervening elements may also be present. In contrast, when an element is referred to as being, for example, “directly on”, “directly attached” to, “directly connected” to, “directly coupled” with or “directly contacting” another element, there are no intervening elements present. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed “adjacent” another feature may have portions that overlap or underlie the adjacent feature.

Spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper”, “lateral”, “left”, “right” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the descriptors of relative spatial relationships used herein interpreted accordingly.

A cabinet 10 according to an embodiment of the present invention is illustrated in FIG. 1 and includes a housing 12 having an opening 14 into an interior 16 in which electronic or communication equipment (not illustrated) is housed. A door 18 is mounted by opening 14 and is connected to the housing by a hinge 20 for allowing access to interior 16 when open and for protecting the contents of the housing from the elements and unauthorized individuals when closed and, optionally, locked. Door 18 includes an outer panel 22 having a plurality of vent openings 24 covered by screens 26 and an inner panel 28 illustrated in FIGS. 2, 3 and 4. Inner panel 28 includes either a single aperture 30 divided into first and second apertures 32, 34 by a cross member 36 as illustrated in FIG. 4, or first and second individual apertures 38 and 40 as illustrated in FIG. 3. A space 42 between the outer panel 22 and the inner panel 28 provides sound and heat insulation and accommodates part of a fan box 44 described hereafter. When only a single fan box 44 is needed, second aperture 34 or second aperture 40 is sealed off by a removable panel 46 mounted thereover as illustrated, for example, in FIG. 2. When it is necessary or desirable to move a greater quantity of air, a second fan box 44′ can be mounted in second aperture 34 or second aperture 40 as illustrated in FIG. 5. Embodiments of the invention using a door 18 having first and second apertures 38, 40 will be discussed herein, it being understood that a door 18 having a single aperture divided into first and second apertures 32, 34 could be used in a similar manner.

Referring now to FIGS. 8 and 9, fan box 44 comprises a frame 48 defining an interior 49 and having a first side portion 50, a second side portion 52, a front side 54 facing in the direction of door outer panel 22 and a rear side 56 facing in the direction of interior 16 when door 18 is closed. First side portion 50 is connected to inner panel 28 next to first aperture 40 by a hinge 58, illustrated in FIG. 5, allowing fan box 44 to pivot away from first aperture 38 as illustrated in FIGS. 6 and 7. Second side portion 52 includes a removable retainer 60 which is described hereinafter. As illustrated in FIG. 9, a first peripheral wall 62 extends around interior 49 of the fan box near front side 54, and a second peripheral wall 64 extends around interior 49 of the fan box, spaced from first peripheral wall 62 in the direction of fan box rear side 56.

A first filter 66 is mounted in a space 68 between first peripheral wall 64 and second peripheral wall 64, and space 68 is selected based on the size of the filter to be used to provide a snug fit for the filter so that substantially all air passing through fan box 44 must pass through first filter 66. First filter 66 is inserted into space 68 through a side entrance 70, illustrated in FIG. 7, which is selectively covered by retainer 60 and secured by suitable fasteners such as screws (not illustrated). Retainer 60 is configured to seat tightly against the first filter 66 to substantially prevent air passing through the fan box from circumventing the first filter 66. First filter 66 may comprise a disposable filter or a reusable filter, and reusable filters sold under the brand name QUADRAFOAM by the Universal Air Filter Company of Sauget, Ill. have been found to be suitable for this application.

A second filter 72 is mounted on the side of second peripheral wall 64 opposite first filter 66 and is held against the second peripheral wall 64 by a fan tray 74 mounted on the rear side 56 of the fan box 44. Second filter 72 comprises a hydrophobic filter configured to substantially prevent the passage of particulate matter that is not trapped by first filter 66 and likewise to substantially prevent water from entering cabinet 10 through fan box 44. A suitable hydrophobic filter is an ePTFE (Expanded Polytetrafluoroethylene) based filter available from W. L. Gore & Associates. Second filter 72 will generally be more expensive than first filter 66, but because second filter 72 filters air that has already been filtered by first filter 66, it will require less frequent cleaning or replacement. Second filter 72, as illustrated in FIG. 9, includes a first flange 76 contacting second peripheral wall 64 of fan box 44 and a second flange 78 contacting fan tray 74 when fan tray 74 is mounted on fan box 44. If a second filter 72 were used that did not include such first and second flanges, separate gasket members (not illustrated) could be used to ensure a substantially air-tight seal between the second filter 72, the second peripheral wall 64 and the fan tray 74.

Fan tray 74 comprises a panel 80 having a first side 82 facing second filter 72 and a second side 84 facing housing interior 16 when door 18 is closed. A plurality of fans 86 are mounted in openings in panel 80 and connected to a suitable controller 88, illustrated in FIG. 10, that provides fans 86 with power and that controls the activation state and speed of the fans. Controller 88 may be connected to fan tray 74 in any conventional manner such as via a wire or cable (not illustrated) that extends from the controller to the fan tray 74 across door hinge 20. A gasket 90 is mounted on first side 82 of panel 80 for forming a substantially air-tight seal with the interior 49 of fan frame 46 and pressing against second flange 78 of second filter 72 when the fan tray 74 is mounted on the fan box 44. A pressure sensor 92 is mounted on second side 84 of panel 80 and operatively connected to controller 88, and a temperature sensor 94 in housing 12 is also operatively connected to controller 88.

The removal of first filter 66 and second filter 72 for cleaning or replacement and the removal of fan tray 74 for repair will now be described. With reference to FIGS. 6 and 7, door 18 is opened to expose fan box 44, and second side portion 52 of fan box frame 44 is removed from first aperture 38 by pivoting the fan box 44 about hinge 58 to expose removable retainer 60. Retainer 60 is removed by loosening screws (not illustrated) to expose first filter 66, and the first filter 66 can be slid out from between first peripheral wall 62 and second peripheral wall 64 and cleaned or replaced. The cleaned or new first filter 66 is then reinserted in space 68 as previously described, retainer 60 is replaced and secured, and fan box 44 is pivoted back into first aperture 38 as shown, for example, in FIG. 2.

Fan tray 74 is mounted to rear side 56 of fan box frame 48, and is readily accessible when door 18 of cabinet 10 is opened. If fan tray 74 or one or more fans 86 on the fan tray 74 require service, they can be directly accessed by opening cabinet door 18. Alternately, fan tray 74 can be removed and replaced with a new fan tray when it is preferable to quickly return the cabinet 10 to service and troubleshoot the defective fan tray at a service facility rather than in the field.

An exit opening 96 is provided on a wall of housing spaced from door 18, such as rear wall 98 illustrated in FIG. 10. Exit opening 96 allows air drawn into housing 12 by fans 86 to leave the housing, taking with it much of the heat produced by equipment operating inside the cabinet 10. Exit opening 96 is selectively blockable by a damper assembly 100 which includes first and second flaps 102 which can be pivoted or otherwise moved between a closed position illustrated in FIG. 10 to an open position, not illustrated, that allows a relatively free flow of air from the interior of the housing 12. An actuator 104 operatively is operatively connected to the controller 88 and to the first and second flaps 102 and positions the first and second flaps 102 based on signals from the controller 88. Dashed line 106 illustrates the position of a vented cover (not illustrated for clarity) that fits over damper assembly 100 to keep animals and insects out of the housing 12 and to minimize the entry of rain.

Controller 88 controls the position of damper flaps 102 based at least in part on input from temperature sensor 94. When the interior temperature of housing 12 exceeds a predetermined temperature, 5 degrees C., for example, controller 88 causes actuator 104 to open flaps 102. When the temperature of the housing interior drops below 5 degrees C., controller 88 closes flaps 102 to retain heat and reduce the need for auxiliary heating of the cabinet. The fans 86 may be turned on and off and operated at different speeds based on the sensed temperature of the housing in a conventional manner.

A method of determining when first filter 66 and/or second filter 72 needs service is also possible with the cabinet 10 described above. According to this method, a first pressure reading is taken by pressure sensor 92 when the fans 86 are in a first operating state, such as off. The fans 86 are then driven at a set speed, such as 60% of their maximum operating speed, and a second pressure reading is taken. The difference between these readings is compared to a predetermined value, and if the difference is less than the predetermined value, a signal is generated by controller 88 to indicate that the filters are at least partially blocked and require service. The predetermined amount may be established from baseline readings taken when first filter 66 and second filter 72 are new. For example, it may be possible to raise the pressure inside housing 12 by 2 psi by running the fans 86 at 60% of their maximum rate when the filters are not blocked. As the first and second filters become increasingly blocked with use, the fans 86 will not be able to draw in air at a high enough rate to increase the pressure in the housing by the same amount. When, for example, the pressure can no longer be raised by 1 psi, it may be time to service the filters. The actual amounts of pressure increase indicative of clean filters and filters that require service can be determined empirically for a particular installation, and controller 88 can run this test on a predetermined basis, daily, for example. A variety of different first and second fan operating states can be selected for performing the above test, such as 10 percent of maximum operating speed for the first state and 80 percent of maximum operating speed for the second test. However, it may be desirable to select a second state that is low enough, such as the 60% of maximum operating speed described above, to avoid the production of excessive turbulence inside the housing which can make it difficult to obtain an accurate pressure reading.

A method related to the above method is illustrated in the flow chart of FIG. 11 which includes a step 110 of providing a sensor in an outdoor communications cabinet housing configured to provide an output based on a sensed pressure of the housing, a step 112 of determining a first level of the output when the at least one fan in the housing is in a first state, a step 114 of determining a second level of the output when the at least one fan is in a second state, a step 116 of determining a relationship between the first level and the second level, and a step 118 of generating a signal when the relationship satisfies a predetermined condition.

The present invention has been described in terms of preferred embodiments. However, modifications and additions to these embodiments will become apparent to those of ordinary skill in the relevant art upon a review of the foregoing disclosure. It is intended that all such modifications and additions comprise a part of the present invention to the extent they fall within the scope of the several claims appended hereto. 

1. An outdoor communication cabinet comprising: a housing having a interior and an opening into said interior; a door connected to said housing at the opening and including a first aperture; and a first fan tray, including a plurality of fans, hingedly connected to said door for movement between first and second positions relative to said first aperture.
 2. The outdoor communication cabinet of claim 1, wherein said door includes a second aperture adjacent said first aperture and further includes either a second fan tray, including a plurality of fans, hingedly connected to said door for movement between first and second positions relative to said second aperture independently of said first fan tray, or a panel removably mounted over said second aperture.
 3. The outdoor communication cabinet of claim 1, including a second fan tray hingedly connected to said door for movement between first and second positions relative to said first aperture independently of said first fan tray.
 4. The outdoor communication cabinet of claim 1, wherein said first fan tray is mounted in a fan box, said fan box being connected to the door by a hinge, said fan box comprising a frame configured to support said first fan tray and at least one filter.
 5. The outdoor communication cabinet of claim 4, wherein said fan box includes a first peripheral wall within said frame configured to sealingly engage a first filter and a second peripheral wall spaced from said first peripheral wall configured to sealingly engage a second filter.
 6. The outdoor communication cabinet of claim 5, including a first filter retained in sealing engagement with said first wall by said fan box frame, a second filter retained in sealing engagement with said second wall by said fan box frame, and a gasket forming a seal between said fan tray and said fan box frame.
 7. The outdoor communication cabinet of claim 4, wherein said door includes an outer panel and an inner panel spaced from the outer panel and defining a space therebetween, said first aperture being located in said inner panel and said fan box being mounted to said inner panel and extending through said first aperture and into said space.
 8. The outdoor communication cabinet of claim 1 including a controller for controlling said plurality of fans of said first fan tray based on a sensed condition and a pressure sensor in said cabinet operatively connected to said controller.
 9. The outdoor communication cabinet of claim 1, including a damper for regulating a size of an exit hole in said housing and a controller for controlling said plurality of fans of said first fan tray and a position of said damper.
 10. The outdoor communication cabinet of claim 8, wherein said controller is configured to measure a first output of said pressure sensor when said plurality of fans of said first fan tray are in a first state, to measure a second output of said pressure sensor when said plurality of fans of said first fan tray are in a second state, and to generate a signal when a difference between said first output and said second output satisfies a predetermined condition.
 11. A method of detecting a degree of blockage of a filter in an outdoor communication cabinet, the cabinet comprising a housing and at least one fan for driving air into the housing and a filter for filtering the air driven into the housing by the at least one fan, said method comprising: providing a sensor in the housing configured to provide an output based on a sensed pressure of the housing; determining a first level of the output when the at least one fan is in a first state; determining a second level of the output when the at least one fan is in a second state; determining a relationship between the first level and the second level; and generating a signal when the relationship satisfies a predetermined condition.
 12. The method of claim 11 wherein the relationship comprises a difference between the first level and the second level and wherein the predetermined condition comprises the difference being less than a predetermined amount.
 13. The method of claim 11, further including: determining a third level of the output when the filter is clean and the at least one fan is in the first state; determining a fourth level of the output when the filter is clean and the at least one fan is in the second state; and using a difference between the third level and the fourth level to establish the predetermined condition.
 14. The method of claim 11 wherein the first state comprises the at least one fan being off and wherein the second state comprises the at least one fan being on and operating at less than full power.
 15. The method of claim 11, wherein the at least one fan comprises a plurality of fans in a fan tray and wherein the housing includes a fan box having a frame for supporting the fan tray and at least one filter, the method including forming a seal between the fan tray and the fan box and mounting the at least one filter in sealing engagement with a portion of the frame such that substantially all air drawn through the fan tray by the plurality of fans is filtered by the at least one filter.
 16. An outdoor communication cabinet comprising: a housing having a interior and a first opening and a second opening into said interior; a door connected to said housing at said first opening; a fan tray, including a plurality of fans, connected to said door; a damper mounted at said second opening for regulating air flow through said second opening; and a controller operatively connected to said plurality of fans and to said damper for controlling operation of said plurality of fans and a position of said damper.
 17. The outdoor communication cabinet of claim 16 wherein said door includes an aperture and wherein said first fan tray is hingedly connected to said door for movement between a first position and a second position relative to said first aperture.
 18. The outdoor communication cabinet of claim 16 including a temperature sensor operatively connected to said controller, wherein said controller controls a position of said damper based on a temperature sensed by said temperature sensor.
 19. The outdoor communication cabinet of claim 18 wherein said controller causes said damper to close when said temperature sensor senses a temperature less than a first predetermined temperature and causes said damper to open when said temperature sensor senses a temperature greater than a second predetermined temperature.
 20. The outdoor communication cabinet of claim 12, wherein said first fan tray is mounted in a fan box, said fan box being connected to the door by a hinge, said fan box comprising a frame configured to support said first fan tray and at least one filter; and a pressure sensor for sensing a pressure of the interior operatively connected to said controller; wherein said controller is configured to measure a first output of said pressure sensor when said plurality of fans of said fan tray are in a first state, to measure a second output of said pressure sensor when said plurality of fans of said fan tray are in a second state, and to generate a signal when a relationship between said first output and said second output satisfies a predetermined condition.
 21. A method of detecting a degree of blockage of a filter in an outdoor communication cabinet, the cabinet comprising a housing having an interior and a first opening and a second opening into the interior, a door connected to the housing at the opening and including an aperture, a fan tray, including a plurality of fans, hingedly connected to the door for movement between first and second positions relative to the first aperture, a damper mounted at the second opening for regulating air flow through the second opening, and a controller operatively connected to the plurality of fans and to the damper for controlling operation of the plurality of fans and a position of the damper, the filter being mounted to said door over said aperture on a side of said first fan tray opposite from said interior, said method comprising: providing a pressure sensor in the housing configured to provide an output based on a sensed pressure of the housing; connecting the pressure sensor to the controller; determining a first level of the output when the at least one fan is in a first state; determining a second level of the output when the at least one fan is in a second state; determining a relationship between the first level and the second level; and generating a signal when the relationship satisfies a predetermined condition. 